This invention relates generally to sound-absorbers, or mufflers, for gas turbine units. More particularly, the present invention relates to mufflers for stationary gas turbine units.
Modern power stations utilize gas turbine units at least in part for the production of steam, whereby these units release not only mechanical energy, which is directly usable by electrical generators, but also a stream of hot gas, which is usable for the production of energy via steam generators. The gas turbine units replace conventional combustion units either completely or partly in this regard.
Gas turbines exhibit relatively high gas velocities at their outlet (exhaust). In addition, the flow is highly turbulent, at least in part, and the gas turbine emits a high level of sound at its outlet. The high flow velocity at the outlet of the gas turbine leads, as a consequence, to a very low static pressure. As a rule, it is necessary to decelerate the gas flow significantly in favor of the static pressure. A diffusor serves for this purpose and is usually formed by a long channel which gradually widens out. In order to achieve the desired diffusor action, the opening angle of this channel, which widens out, is not permitted to be too large. This leads to construction lengths of significantly more than 10 m, for example 13 m, in the required cross-sectional enlargements of the flow channel with conventional diffusor entrance cross sections.
If, however, the static pressure of the gas stream has been increased by controlled deceleration in the diffusor, then a considerable level of sound is still present which needs to be reduced. Thus mufflers are usually provided in the case of conventional gas turbine units and these mufflers are connected to the diffusor in question. Thus, in total, a relatively voluminous plant arises, which is connected to the gas turbine, whereby the plant comprises the diffusor and a serially connected muffler. This plant not only occupies valuable construction space but it generally exhibits an undesirably high back-wash or pressure loss. This reduces the output of mechanical energy by the gas turbine.